A safety razor generally comprises a handle and a blade unit carried on the handle and including at least one blade with a sharp cutting edge. In the course of shaving, the blade unit is applied against the skin and the blade or blades are moved across the skin so that the sharp cutting edges engage and cut through the hairs protruding from the skin. The blade unit can be fixed on the handle with the intention that the entire razor should be discarded when the cutting edges have become dull and are no longer capable of providing a comfortable shave. Alternatively, the blade unit may be removably mounted on the handle so that the blade unit can be replaced by a new blade unit when the sharpness of the blades has diminished to an unacceptable level. Replaceable blade units are often referred to as shaving cartridges.
It is known to include electrically operated vibration mechanisms in safety razors, e.g., as disclosed in EP-A-0885698, U.S. Pat. No. 6,481,104 B1 and U.S. Pat. No. 5,046,249. Other forms of electrical device can also be provided in a safety razor and U.S. Publication No. 2002/0189102 describes a razor including force sensors and an indicator to signal when the blades need to be replaced.
The prior art also includes proposals to include water detectors in association with electrical equipment, for example to detect leaks from domestic appliances as taught by GB-A-2377995, to prevent operation of a coffee maker when the water tank is empty as disclosed in DE-A-3122521, or to switch of a heater when the water level in a fish tank is low as described in JP-A-9051740.
For a long time it has been known that safety razors are advantageously constructed to facilitate cleaning, that is the removal of shaving debris and soap which tend to collect on the blade unit, by rinsing in water. In more recent times it has become appreciated that effective rinsing plays an even more important role than previously recognized and makes a significant contribution to overall razor performance.